This invention relates generally to wind turbine generators and, more particularly, to dissipating thermal energy generated by wind turbine generator components.
Recently, wind turbine generators have received increased attention as an environmentally safe and relatively inexpensive alternative energy source. With this growing interest, considerable efforts have been made to develop wind turbine generators that are reliable and efficient.
Generally, a wind turbine generator includes a rotor having multiple blades. The rotor is mounted on a housing or nacelle, which is positioned on top of a truss or tubular tower. Utility grade wind turbine generators (i.e., wind turbine generators designed to provide electrical power to a utility grid) can have large rotors (e.g., 30 or more meters in diameter). Blades on these rotors transform wind energy into a rotational torque or force that drives one or more generators, rotationally coupled to the rotor through a gearbox or directly coupled to the rotor. The gearbox, when present, steps up the inherently low rotational speed of the turbine rotor for the generator to efficiently convert mechanical energy to electrical energy, which is fed into a utility grid.
The varying rotational speed of the rotor and the unpredictable and inconsistent thermal conditions within the hub provide thermal condition problems within wind turbine generators. Heat generators, including heat-sensitive electronic components stored within an enclosure within the hub, typically generate a significant amount of heat during typical wind turbine generator operation. Component life is typically extended if an internal temperature within the enclosure remains below a failure temperature. Conventional cooling systems for the generator components have been developed to counteract the significant amount of heat generated within the hub. Such conventional cooling systems include air cooled ventilation systems and water cooled systems. These conventional systems are typically complex and require additional components to facilitate cooling. Additionally, these conventional systems require maintenance and power to operate. These factors add cost to the operation of the wind turbine generator.